NFS behavior in Fedora

[Emanuel Machado]

Hi,

 

I wonder if any one is familiar with the following, and may help explain
what is happening:

 

I have a Gigabit dedicated connection between two computers: one running
Enterprise Linux 3 (EL3), and the other running Fedora Core 5 (FC5). I
established an NFS connection in which FC5 exports a directory and EL3
mounts it.

 

I then start an application in EL3 that gets some "hard real time" data and
writes it out to FC5. It is a streaming process, so it would be nice to do
this for an extended amount of time.

 

With this configuration, once the run starts I can see network activity all
the time, and activity on the drive in FC5 writing the data. Really looks
good. Unfortunately we have occasional events that take a little bit longer
than we can afford (hiccups), and the whole thing has to stop.

 

In trying to find out what the longer event is, I tried to upgrade from EL3
to FC5, i.e. both computers running Fedora Core 5. All the settings being
exactly the same, I see a completely different behavior: Now as I start the
run, I don't immediately see any network activity or hard-drive write
activity. When I finally see it, it happens at the same time that I get a
much longer hiccup.

 

It appears that it wants to accumulate in a local buffer long enough (about
100 MB) before it starts sending stuff, just that the buffer is way bigger
than before for some reason. EL3 is using kernel 2.14.21, FC5 is the
"bordeau" dist. I've tried to tinker with NFS parameters (async, block
sizes, etc) but wasn't able to reproduce the EL3-FC5 scenario.

 

Any idea what has changed? 

 

Thanks, 

 

Emanuel

 

----

Emanuel Machado, PhD.

Senior Engineer, Project Leader

 

 

 

Cytonome, Inc.

27 Drydock Ave

Boston, MA 02210

Voice:  (617) 330-5030 ext. 237

Fax:      (617) 330-5031

Website: www.cytonome.com

 

Email: Emanuel-Machado at cytonome.com

 

 

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